Progress of CRISPR‐Cas Based Genome Editing in Photosynthetic Microbes

The carbon footprint caused by unsustainable development and its environmental and economic impact has become a major concern in the past few decades. Photosynthetic microbes such as microalgae and cyanobacteria are capable of accumulating value‐added compounds from carbon dioxide, and have been regarded as environmentally friendly alternatives to reduce the usage of fossil fuels, thereby contributing to reducing the carbon footprint. This light‐driven generation of green chemicals and biofuels has triggered the research for metabolic engineering of these photosynthetic microbes. CRISPR‐Cas systems are successfully implemented across a wide range of prokaryotic and eukaryotic species for efficient genome editing. However, the inception of this genome editing tool in microalgal and cyanobacterial species took off rather slowly due to various complications. In this review, we elaborate on the established CRISPR‐Cas based genome editing in various microalgal and cyanobacterial species. The complications associated with CRISPR‐Cas based genome editing in these species are addressed along with possible strategies to overcome these issues. It is anticipated that in the near future this will result in improving and expanding the microalgal and cyanobacterial genome engineering toolbox. Since its inception in 2013 as a genome editing tool, CRISPR‐Cas systems has revolutionized the genetic engineering in various model and non‐model organisms. The application of this tool in the microalgal species are hindered by the hypothesised toxic effect of Cas9 in these organisms. Since 2016, there has been a considerable growth in implementing CRISPR‐Cas based genome editing in microalgal and cyanobacterial organisms. This work provide a concise overview on the progress of achieving CRSISPR‐Cas based genome editing in microalgae and other photosynthetic microbes.